On Performance of Fluid Antenna System using Maximum Ratio Combining

TL;DR

This paper analyzes the performance of a fluid antenna system with multiple ports, focusing on outage probability and diversity gains when selecting and combining the best ports using MRC in Rayleigh fading channels.

Contribution

It introduces an analysis of fluid antenna systems with multiple port selection and MRC, providing new insights into their outage performance and diversity benefits.

Findings

FAS can achieve significant spatial diversity gains.

Analytical outage probability matches simulation results.

High SNR approximations provide useful performance insights.

Abstract

This letter investigates a fluid antenna system (FAS) where multiple ports can be activated for signal combining for enhanced receiver performance. Given $M$ ports at the FAS, the best $K$ ports out of the $M$ available ports are selected before maximum ratio combining (MRC) is used to combine the received signals from the selected ports. The aim of this letter is to study the achievable performance of FAS when more than one ports can be activated. We do so by analyzing the outage probability of this setup in Rayleigh fading channels through the utilization of Gauss-Chebyshev integration, lower bound estimation, and high signal-to-noise ratio (SNR) asymptotic approximations. Our analytical results demonstrate that FAS can harness rich spatial diversity, which is confirmed by computer simulations.